Refreshing a Custom Model data (QList<UserDefinedClass>) and swapping the lists contained in a QMap

Andrea_Venturelli

Hello everyone, what I'm trying to implement is the following QMainWindow made of the components:

left QListView do not exist for the moment and is simulated to simplify testing, so don't focus to much on it.
GroupEditor (righ Widget) uses a custom model (PathsInfoTableModel) that is set to the QTableView

2.1) This widget as a Custom Card ( visible under the QTableView on the image above) and is simply a QWidget with a
QDataWidgetMapper that is connected to the QTableView currentItem that is called MapperPathInfo.

The application's storage Structure:

// QMap< QString, QList<PathInfo> >

"GroupName1"
{
      [ 
          Path_info_1,
          Path_info_2,
          ... ,
          Path_info_12,
      ]
},
"GroupName2"
{
      [ 
          Path_info_1,
          Path_info_2,
          ... ,
          Path_info_7,
      ]
}

Functionality Description:

In the main window constructor a customModel called PathsInfoTableModel( QList<PathInfo> data) is istanciated and then passed to the GroupEditor's constructor (right widget) for the QTableView and is forwarded to the Widget mapper MapperPathInfo that set also QDataWidgetMapper->setModel( m_model )

long story short, a customModel is istanciated in the main window and then shared to QTableView and a QDataWidgetMapper

When the user want to edit a group (that contains a QList of paths obj) he clicks the "Edit Group"
-> this will take the "GroupName" as a QString and use it as a key in the QMap to retrive the corresponding QList<PathInfo>
and set the model's internal data structure to that QList

auto current_list = (*QMap)["GroupName2"];
//definition in the model: void setListData( QList<PathInfo>& new_paths_list );
customModel->setListData( current_list);

model definition:


class PathsInfoTableModel : public QAbstractTableModel
{
    Q_OBJECT
public:
    explicit PathsInfoTableModel( QList<PathInfo> group= QList<PathInfo>(), QObject *parent = nullptr );


    // virtual override
    int rowCount( const QModelIndex &parent = QModelIndex() ) const override;
    int columnCount( const QModelIndex &parent = QModelIndex() ) const override;

    QVariant data( const QModelIndex &index, int role = Qt::DisplayRole ) const override;
    bool setData( const QModelIndex& index, const QVariant& value, int role ) override;

    QVariant headerData(int section, Qt::Orientation orientation, int role = Qt::DisplayRole) const override;

    Qt::ItemFlags flags(const QModelIndex &index) const override;

    QList<PathInfo>& getPathInfoList() { return m_model_data; }
    void setListData( QList<PathInfo>& new_paths_list );

private:
    QList<PathInfo> m_model_data;

};

model implementation:


PathsInfoTableModel::PathsInfoTableModel(QList<PathInfo> group, QObject *parent)
    : QAbstractTableModel{parent}, m_model_data{ group }
{}


Qt::ItemFlags PathsInfoTableModel::flags(
    const QModelIndex &index
) const
{
    if ( !index.isValid() ) return Qt::NoItemFlags;

    // sets path_col and IsOpenable_col editable
    if ( index.column() == 3 )
    {
        return Qt::ItemIsEditable | Qt::ItemIsEnabled | Qt::ItemIsSelectable;
    }

    return Qt::ItemIsEnabled | Qt::ItemIsSelectable;
}


int PathsInfoTableModel::rowCount(
    const QModelIndex &parent
) const
{
    Q_UNUSED(parent)
    return m_model_data.size();
}


int PathsInfoTableModel::columnCount(
    const QModelIndex &parent
) const
{
    Q_UNUSED(parent)
    return 4;
}


QVariant PathsInfoTableModel::data(
    const QModelIndex &index,
    int role
) const
{

    auto col = index.column();
    auto row = index.row();
    PathInfo p = m_model_data.at(row);

    // add pixmap to first and third column
    if ( role == Qt::DecorationRole && (col == 0 || col == 2) )
    {
        auto is_path_valid = p[2].toBool();

        // select the right icon for
        // the first column
        if ( col == 0 )
        {
            // path doesn't exist
            if ( !is_path_valid )
                return p.NOT_A_FILE_PIX;

            // exists and is a file
            if ( p[0].toBool() )
                return p.FILE_PIX;

            // is a folder
            return p.FOLDER_PIX;
        }

        return ( is_path_valid ) ? p.VALID_PIX : p.INVALID_PIX;
    }

    if ( role == Qt::DisplayRole && col == 1 )
    {
        return p[col];
    }

    /****************************************************************************
     * change it with a custom QStyledItem
     * to draw the chips instead
     ****************************************************************************/
    // add text Valid-Invalid
    if ( role == Qt::DisplayRole && col == 2 )
    {
        return ( p[col].toBool() ) ? QVariant( QString("Valid") ) : QVariant( QString("Invalid") );
    }


    return QVariant();
}


bool PathsInfoTableModel::setData(
    const QModelIndex& index,
    const QVariant& value,
    int role
)
{
    auto row = index.row(), col = index.column();
    QModelIndex fileTypeIdx = createIndex(row, 0);
    QModelIndex validityIdx = createIndex(row, 2);

    if ( !index.isValid() || row >= m_model_data.size() )
        return false;


    if ( role == Qt::DisplayRole || role == Qt::EditRole )
    {
        // get PathInfo at row index.row()
        PathInfo& pathInfo = m_model_data[row];

        if ( col == 1 )          // edit the path_column
        {
            // not a path, return
            if ( !value.canConvert<QString>() ) return false;

            QString oldPath = pathInfo.path();
            pathInfo.changePath( value.toString() );

            if ( oldPath != pathInfo.path() )
            {
                emit dataChanged( index, index, { Qt::DisplayRole, Qt::EditRole } );
                emit dataChanged( fileTypeIdx, fileTypeIdx, { Qt::DisplayRole } );
                emit dataChanged( validityIdx, validityIdx, { Qt::DisplayRole } );
                return true;
            }

            return true;

        }
        else if ( col == 2 ) // edit the isValid chip
        {
            // check if data is of type bool
            if ( !value.canConvert<bool>() ) return false;

            bool old_state = pathInfo.pathValidity();

            // checks if path is valid
            pathInfo.checkPathValidity();

            if ( old_state != pathInfo.pathValidity() )
            {
                // update FileType and ValidityChip col
                emit dataChanged( fileTypeIdx, fileTypeIdx, { Qt::DisplayRole } );
                emit dataChanged( validityIdx, validityIdx, { Qt::DisplayRole } );
                return true;
            }

            return true;
        }
        else if ( col == 3 ) // edit the isOpenable_col
        {
            if ( !value.canConvert<bool>() ) return false;

            pathInfo.setOpenable( value.toBool() );
            emit dataChanged( index, index, { Qt::DisplayRole, Qt::EditRole } );
            return true;
        }

        return false;
    }

    return false;
}


QVariant PathsInfoTableModel::headerData(
    int section,
    Qt::Orientation orientation,
    int role
) const
{
    if ( orientation != Qt::Horizontal || role != Qt::DisplayRole ) return QVariant();

    switch ( section ) {
    case 0:
        return "Type";
    case 1:
        return "Full Path";
    case 2:
        return "Validity State";
    case 3:
        return "Openable";
    default:
        return QVariant();
    }
}


void PathsInfoTableModel::setListData( QList<PathInfo>& new_paths_list )
{
    beginResetModel();
    m_model_data = new_paths_list;
    endResetModel();
}

Andrea_Venturelli

I have to make 2 different post because the first was getting to long.

the problems:

there is something in the model resetting when a change the old QList with the new QList retrived from the QMap that is causing segmentation fault. I Post the full code on gitHub (https://github.com/aVenturelli-qt/ArchWay-Project-Manager) because it will never fit to the forum.

How can I have a model pointing to QList stored in a QMap that can be directly modified by the model and when i'm done editing it and switch to a dfferent Qlist (also contained in the QMap but inside a different key) a can reset the Model with new Data ?

Pl45m4

@Andrea_Venturelli said in Refreshing a Custom Model data (QList<UserDefinedClass>) and swapping the lists contained in a QMap:

beginResetModel();
m_model_data = new_paths_list;
endResetModel();

I would have suggested exactly this now...
This doesn't work for you?!

Reset the model when you switch to new list and assign the new one to update all views

Andrea_Venturelli

commenting out the instanciation of the left widget will prevent the segmentation fault problem, so the problem mist be in some custom slot where i update the values after the “modelChanged()” signal.

it seems like the model exist for all the component that uses it but when accesing the have a reference to some non existing data and crush..

without a deep knowledge of QMap<> i think I’m missing some core concepts that is casuing the problem after the model resetted